Growth factor, known as polypeptide growth factor customarily, is a group of proteins regulating the growth and differentiation of cells and has molecular weight from several hundred to dozens of kilodalton (KD). It is revealed that the regulation of cell growth is mediated by a series of cascade reactions triggered by the interaction between a variety of cytokines and their specific receptors on membrane surfaces. Compared to classical polypeptide and protein hormone, growth factor is released by autocrine and paracrine cells instead of endocrine gland or endocrine cells, so as to achieve the coordination of body and reaction to the environment.
Hepatoma derived growth factor (hepatoma derived growth factor, HDGF) is an important growth factor, which was first reported in paper by Klagsbrun, M et al. in 1986 (P.N.A.S. USA Vol. 33, pp 2448-2452, 1986). In this paper, Klagsbrun, M et al. reported to have isolated and purified a protein factor having 18.5-19 KD from human hepatoma cells line SK-HEP-1. And the remarkable character of this factor was its strong affinity with heparin.
In 1989, a 64 KD factor, also named as HDGF, was first partially purified from HuH-7 cells and characterized by Nakamura et. al. (Clin. Chim. Acta. 183:273-284, 1989). This research group had studied its biochemical characteristics and functions, and found that HDGF was different from PDGF, FGF, HGF. In 1997, this group found the mouse homologue of human HDGF as well as other two members of the gene family, HRP-1 and HRP-2. They all had a highly conserved N-terminal of 98 amino acids. (Biochem. Biophys. Res. Commun. 238: 26-32,1997). In 1999, this research group also cloned HRP-3 (Biochem. Biophys. Res. Commun. 266(1):81-87,1999), another member of HDGF family from human and mouse.
Prior to the publication of this invention, none has disclosed human HDGF5 of the present application.